The technological importance of thin films has led to a multitude of deposition methods whose diversity can be seen by way of reference to many textbooks, including "Handbook of Deposition Technologies for Films and Coatings" by R. Bunshah published by Noyes Publishing Co. Park Ridge N.J. (1994). There is an ever growing need to develop innovative and economical techniques for manufacture of complex materials having controlled properties. A family of vapor deposition processes have been developed by the assignee of the present invention and are referred to with the trademark Jet Vapor Deposition (JVD). The JVD processes have shown advantages over established methods derived, in part, from the unique "low vacuum" operating regime and from the novel vapor sources that exploit that regime.
Vapor deposition methods are divided traditionally into Chemical Vapor Deposition (CVD) and Physical Vapor Deposition (PVD), according to the means of generating film components. In CVD, precursor molecules react at the substrate, usually at elevated temperature and pressure, to yield film components. In PVD, film components are generated some distance from the substrate, usually in high vacuum; the gas phase mean free path is large, and film species travel "line of sight" to the growing film. A JVD process, however, does not fit this traditional description.
In a JVD process, film components are generated remotely, as in PVD, but the vacuum is "low", and the mean free path small. Film components travel "line of sight", but not through collision free space. Instead, the film components are convected to the substrate in a collimated, sonic, inert gas "jet in low vacuum". Exemplary processes set forth in the aforementioned patents include one based on microwave discharge chemistry which is capable of depositing metals and other materials such as silicon (Si). A second process uses a "wirefeed/hot filament" and is useful for depositing at extremely high rates copper (Cu), gold (Au), and silver (Ag), and, with some constraints, low melting metals aluminum (Al), zinc (Zn), tin (Sn), antimony (Sb), indium (In), and cadmium (Cd).
Sources of metal vapor are known in the art. For example, electron beam vaporization is capable of ultra-high metal throughputs, but the efficiency of power usage is low, X-rays must be considered, and expensive high vacuum apparatus is normally needed. Laser ablation in principle can give high rates, but the lasers required are bulky and expensive. In other systems, metal-organic chemistry can be used for metal atom generation, but the gaseous precursors are toxic and expensive, and require careful gas handling.
Known systems are limited in the metals which can be vaporized or in the deposition rates which can be achieved. It would be advantageous to have a system that offers a combination of two important and sought-after features: high rate deposition, and film property control. The present invention is drawn towards such a system. A system provided in accordance with the present invention can vaporize virtually any metal at high rate. It also represents a breakthrough in the control of microstructure in a growing film as the substrate can be bombarded with ions at controllably low energy and extreme high flux.